The present invention relates to a turbomachine wheel having blades mounted on a rotor comprising an annular peripheral ring in which are formed open axial recesses each of which receives the root of a blade.
Each blade is radially retained in its recess so as to resist the effects of centrifugal force by cooperation of complementary shapes of the mortise-and-tenon type fastener whose fitting direction is parallel to the axis of the rotor, the root of each blade having if desired in particular in section in a radial plane, a toothed shape termed "fir tree root".
The root of each blade is axially immobilized in its recess by two annular flanges placed on the opposite sides of the rotor, the flanges at least partly closing the opposed axial ends of the recesses for the roots of the blades and thereby performing the function of closing covers for these recesses.
In the design of such a wheel of a turbomachine, and in particular of a turbine of an aircraft or helicopter engine, it is of course necessary to maintain the blades or vanes of the turbine in position as perfectly as possible so as to avoid any vibrations, in particular under the effect of centrifugal force which is considerable owing to the high speeds of rotation attained in this type of application. The annular flanges forming covers therefore perform an essential function for the turbine and must be fixed in a precise and reliable manner on the rotor on which the blades are mounted directly or indirectly.
For this purpose, it is desirable to have available flange fastening means the weight of which is reduced to a minimum. It is also desirable to be able to eliminate any connection or fastening of the screwthreaded type, for example bolts or studs and nuts, this type of fastening being particularly heavy and involving considerable risks of accidental disassembly under the effect of the vibrations.
The fastening means must also continue to perform their function under the best possible conditions and with all the required reliability at the different temperatures of operation of the turbomachine whose component parts are subjected to considerable thermal shocks.